1. Field of the Invention
The present invention relates to a TV signal determining system, a TV signal processing system utilizing which and method thereof, and particularly relates to a TV signal determining system for determining the type of TV signal according to the profile thereof, a TV signal processing system utilizing which and method thereof.
2. Description of the Prior Art
FIG. 1 is a block diagram illustrating a prior art TV signal processing system 100. As shown in FIG. 1, the TV signal TS is first sampled by an ADC (analog to digital converter) 101 and then processed by a video decoder 103.
As known by persons skilled in the art, a TV signal includes a color sub-carrier, and a frequency of which varies corresponding to a standard thereof (for example, PAL, NTSC, and SECAM). If the video decoder 103 wants to correctly decode the TV signal, the standard of the TV signal must be obtained first, thus the frequency of the color sub-carrier should be detected before decoding. Conventionally, if the video decoder 103 wants to detect the frequency of the color sub-carrier, it must lock the h-sync signal and v-sync signal of the TV signal first, thereby obtaining the color sub-carrier with the correct timing. Then a PLL (Phase Lock Loop) circuit must be utilized to lock the frequency and phase of the color sub-carrier such that a level of VCO can be obtained and the frequency of the color sub-carrier can be detected.
However, such a mechanism for detecting the frequency of a color sub-carrier is complicated and needs a lot of time.